No. 224 · Strategy · Game Theory
Nash Equilibrium
A stable outcome is one where nobody gains by changing course alone, even if all would gain together.
In the Almanac
“Nash’s short paper”, 1950 · “Tesco”, 2020–2021
Both stories in full, three ways to use it and where it misleads.
Get the AlmanacQuestions
What is Nash Equilibrium?
A Nash Equilibrium is a situation where no player can do better by changing strategy alone, given what others are doing. John Nash defined it in 1950, aged 21. UK supermarkets matching Aldi's prices show it: cutting deeper invites matching, raising prices loses shoppers.
How do you use Nash Equilibrium?
When a situation feels stuck, map each person's best response. Stable does not mean good, so look for ways to change the rules or coordinate with others to reach a better outcome.
When does Nash Equilibrium matter?
Nash Equilibrium is one of the 56 mental models for strategy, the situations where you ask: How do I win when others want the same thing? Within that, it belongs to “Competing with rivals”, alongside Arms Race, Asymmetric Warfare and Beachhead Strategy.
What is an example of Nash Equilibrium?
Two stories show it at work: Nash’s short paper (1950) and Tesco (2020–2021). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.
Which mental models are related to Nash Equilibrium?
Prisoner’s Dilemma, Game Theory and Homeostasis. Nash Equilibrium itself comes from game theory.